This invention relates to a ventilating device for a generator of the type having a rotor stator unit arranged in a housing with air ducts and with a fan wheel on the shaft of the rotor.
A generator is known from No. DE-OS 32 11 502 which is arranged in a housing having air guiding ducts and cooling air outlets. Via a fan wheel located within the housing and close to a front wall, air entering against the driving direction of the vehicle through outside openings is pressed into and through the housing. On the front side and outside the housing, a pulley is disposed on a shaft of the generator rotor, said pulley partially covering the outside openings and preventing an unimpaired air supply for the cooling of the generator rotor and stator. This impairment of the air current results in an increase of the noise emission which, in a disadvantageous manner, is increased even more by a relatively narrow and labyrinth-type air guiding within the housing to the air outlets.
It is an objective of the invention to provide a ventilating device for a generator of the initially mentioned type by means of which an efficient cooling and ventilating effect is achieved, aiming at the same time at a simultaneous clear lowering of the noise emission.
By means of an advantageous guiding of the air current which permits a supply of cooling air through the supporting ribs of the air delivery wheel, an air guiding is achieved near the rotational axis. As a result a favorable flow against the fan wheel (small flow duct diameter) can be obtained, or a fan wheel can be realized that has favorable dimensions with respect to flow mechanics and acoustics, such as a smaller outside diameter.
Because of the streamlined forwarding of the air current to the rotor-stator unit or to the thermally sensitive electric and electronic components, an efficient cooling takes place with an improved efficiency as compared to the known construction according to No. DE-OS 32 11 502. The pulley is also designed as an air delivery wheel and at the same time leads the supplied air in a compressing manner to the fan wheel connected at the outlet side. By means of the supply that is unimpaired from the outside and the streamlined entering of the air current from the radial outflow from the fan wheel into the cylindrical part of the housing via a curved air guiding surface of a closing cover, flow resistances are avoided and a possible generating of noise is counteracted. Because of the cover effect, the housing also contributes to the muffling of air sounds.
In addition, because of the expanding space in the housing downstream from the fan wheel, the radially emerging air current of relatively high speed is slowed down in such a way that during the entering into the air ducts, no additional noises can occur.
By means of the air guiding, a targeted flow through the generator is achieved from the front toward the rear.
The supply with cold cooling air takes place directly from the front side of the vehicle. Also in the case of a supply of air via a hose, this arrangement is advantageous because the hose can be kept short and can be constructed without any deflection.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.